Summary Of Significant Accounting Policies (Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2012 Ecova [Member]	Mar. 31, 2012 Other [Member]	Dec. 31, 2011 Other [Member]	Mar. 31, 2012 Accumulated Impairment Losses [Member]	Dec. 31, 2011 Accumulated Impairment Losses [Member]
Goodwill [Line Items]
Balance at beginning	$ 39,045	$ 33,799	$ 12,979	$ 12,979	$ (7,733)	$ (7,733)
Goodwill acquired during the period	33,484	33,484
Adjustments	1,254	1,254
Balance at ending	$ 73,783	$ 68,537	$ 12,979	$ 12,979	$ (7,733)	$ (7,733)